1. Field of the Invention
The present invention relates to an alarm apparatus, in particularly, an alarm apparatus and its method which is used in a mobile communication network between a base station and at least one mobile phone movable inside a use prohibition area from an outside area thereof.
2. Prior Art
In a matter which will later be described in details, such an alarm apparatus and its method as to a user of its mobile phone in a use prohibition area are already known upon laying open of the following patent documents. As a first prior art apparatus, a patent document No. 1 is disclosed in Japanese Patent application, Unexamined Prepublication (A) Kokai No. JP1999-331061A entitled “Use Prohibition Alarm System of Mobile Phone”. According to this first prior art apparatus, when a user with a mobile phone kept in a power-on mode is present inside the use prohibition area, an alarm sound indicative of a prohibition to the user is generated. In order to achieve such an alarm apparatus, a shield pass for shielding a down signal from a base station is provided with an entrance of the use prohibition area. When the user moves inside the use prohibition area through an exit of the shield pass, a dummy base station generates a quasi-down signal for sending the mobile phone, so that the mobile phone receives the quasi-down signal and generates an up signal for carrying out a positioning registration operation. Inasmuch as a receiver for detecting the up signal is provided with the exit of the shield pass, a speaker broadcast an alarm.
Furthermore, a patent document No. 2 is disclosed in Japanese Patent application, Unexamined Prepublication (A) Kokai No. JP2002-95053A entitled “Use Administration System of Mobile Phone”. According to this second prior art apparatus, an electric wave shield pass is provided as an intrusion pass for entering a use prohibition area. In the intrusion pass, the second prior art apparatus comprises a transmission unit for transmitting a control signal to an intruded mobile phone, a reception unit for a response signal from an intruded mobile phone, and an alarm unit for producing an alarm indicative of “Switch off” when the reception unit is receives the response signal. As a result, it prevents the user from forgetting to set in a switching-off mode of the mobile phone.
Likewise, a patent document No. 3 is disclosed in Japanese Patent application, Unexamined Prepublication (A) Kokai No. JP2001-28618A entitled “Use Alarm Apparatus for Mobile Phone”. According to this third prior art apparatus, an electric wave from a mobile phone is detected by both a parent detector and a plurality of child detectors equipped within a use prohibition area monitored by an administrator. Both a user of the mobile phone and the administrator receive an alarm.
As for the first prior art apparatus, the intrusion pass and the dummy base station are provided therewith, so that a large-scale equipment is needed.
Also, as for the second prior art apparatus, the transmission unit, the reception unit, and the alarm unit are provided therewith, so that a large-scale equipment is needed.
Furthermore, in the third prior art apparatus, when a lot of mobile phones are entered therein, it is difficult for such users to find out who is alarmed, in such a case that any of the users judges not to be alarmed and ignores the alarm at worst. Therefore, it is disadvantageous in that the alarm apparatus cannot inform the users of use prohibition area of the mobile phones, so that the alarm apparatus is of no use.